JP2016523131A - Gastrointestinal capsule position estimation - Google Patents

Abstract

A system for estimating the position of a contrast capsule for inspecting a user's digestive tract, comprising: a contrast capsule for inspecting a user's interior; and a recorder for communicating with the contrast capsule from outside the user Including. The contrast capsule includes a controller that controls the function of the contrast capsule, a transceiver that communicates with the recorder, and a coil that transmits electromagnetic signals. The recorder includes a controller that controls the function of the recorder, a transceiver that communicates with the contrast capsule, and a coil that receives an electromagnetic signal from a coil of the contrast capsule. In this, the recorder determines the position of the contrast capsule based on the measured value of the amplitude of the electromagnetic signal transmitted by the coil of the contrast capsule. [Selection] Figure 1

Description

RELATED APPLICATIONS This application is filed in US Provisional Application No. 61 / 831,163, filed June 5, 2013, US Provisional Application No. 61 / 903,998, filed November 14, 2013, and January 2014. This application claims priority from US Provisional Application No. 61 / 931,742 filed on the 27th, the disclosure of which is incorporated herein by reference.

  The present disclosure relates generally to using an intraluminal capsule to explore the patient's colon, and more particularly to estimating the position of the capsule as it travels through the gastrointestinal tract.

  One way to examine the gastrointestinal tract for the presence or absence of polyps and other clinically relevant features that may provide signs of cancer potential It is done to swallow a contrast capsule for viewing. In a typical case, this transfer takes 24 to 48 hours, after which the contrast capsule is drained into the patient's stool. Typically, a patient drinks a contrast agent to enhance the contrast ability of the contrast capsule. The patient swallows the contrast capsule while the contrast agent is flowing, and examines the digestive tract. The contrast capsule typically includes a radiation source including a radioisotope that emits, for example, X-rays or gamma rays. This radiation is typically collimated and can be controllably directed in a particular direction during the imaging process. In some cases, the imaging capsule measures Compton backscatter and / or fluorescent X-rays and wirelessly transmits this measurement (eg, count value) to an external analyzer, such as a computer or other dedicated equipment. Designed to do.

  In one exemplary embodiment, radiopaque contrast agents are used to reduce contrast at certain locations of the polyp and to measure larger backscatter counts to improve the accuracy of the measurements. Alternatively, the digestive tract may be imaged using other methods.

  The disclosure of Kimchy US Pat. No. 7,787,926, which describes details related to the manufacture and use of such contrast capsules, is incorporated herein by reference.

  The use of contrast capsules exposes the user to radiation and is potentially harmful. Therefore, it is important to limit the user's exposure to radiation when not needed, for example to emit only when needed and block radiation from being emitted from the capsule when not needed. The contrast capsule may be designed with a sealing mechanism that can be instructed to block radiation when not needed for scanning. If necessary, this sealing mechanism is normally in the closed position and prevents radiation from being emitted from the capsule when not being scanned.

  In one exemplary embodiment, the imaging capsule need not be scanned repeatedly at the same location, so it can be instructed to selectively scan with radiation only when the capsule changes position in the colon. it can. By using selective scanning, energy can also be maintained, thus extending battery life and / or using smaller size batteries.

  Therefore, it is preferable to keep track of the capsule position continuously so that the capsule can be instructed to emit when the position changes or when the capsule reaches a specific destination position. Furthermore, tracking the position of the capsule as it travels through the gastrointestinal tract helps to find the position of detected polyps or other obstacles and form an accurate three-dimensional map that helps to treat.

  One aspect of embodiments of the present disclosure relates to a system and method for estimating the position of a contrast capsule in a user's body. The system includes a contrast capsule that is swallowed by the user and a recorder located outside the user's body, for example, on the user's back or waist belt. The contrast capsule includes a controller that controls the function of the contrast capsule and a transceiver that communicates with the recorder to receive instructions or provide information. Further, the contrast capsule includes, for example, a coil that transmits a low-frequency electromagnetic signal.

  The recorder also includes a controller that controls this function and a transceiver that communicates with the imaging capsule. In addition, the recorder includes one or more coils that receive electromagnetic signals transmitted by the contrast capsule.

  The controller of the recorder is programmed to analyze the amplitude of the received electromagnetic signal and determine the position of the contrast capsule based on this electromagnetic signal.

  In some embodiments of the present disclosure, the imaging capsule coil may be a one-dimensional coil with windings in a single plane, or may have windings in two or three planes orthogonal to each other. (2D or 3D). Similarly, the coils in this recorder may have windings in a single plane or two or three orthogonal planes.

  In one exemplary embodiment of the present disclosure, the imaging capsule coil has a 3D coil and is designed to transmit simultaneously in three orthogonal directions at different frequencies. Alternatively, the coils of the contrast capsule may be sequentially transmitted in three orthogonal directions.

  In an exemplary embodiment of the present disclosure, the recorder receives at least two 3D coils for receiving a signal transmitted by the imaging capsule coil and determining the position of the imaging capsule based on the transmission. Have.

  In an exemplary embodiment of the present disclosure, both the imaging capsule and the recorder include an accelerometer and a magnetometer that identify the movement of the imaging capsule. If necessary, the contrast capsule accelerometer and magnetometer display is sent to the recorder through the transceiver and compared to the recorder accelerometer and magnetometer display to determine the spatial orientation of the contrast capsule. . In an exemplary embodiment of the present disclosure, the spatial orientation along with the amplitude of the electromagnetic signal received by the recorder coil is used to determine the position of the contrast capsule relative to the recorder and the distance between them.

  Thus, in an exemplary embodiment of the present disclosure, a system for estimating the position of a contrast capsule for examining the user's digestive tract is provided, the system comprising a contrast capsule for examining the interior of the user. And a recorder that communicates with the contrast capsule from outside the user, the contrast capsule including a controller that controls the function of the contrast capsule, a transceiver that communicates with the recorder, and a coil that transmits electromagnetic signals. The recorder includes a controller that controls the function of the recorder, a transceiver that communicates with the contrast capsule, and a coil that receives an electromagnetic signal from the coil of the contrast capsule. Based on the measured amplitude of the transmitted electromagnetic signal, the position of the contrast capsule is determined.

  In one exemplary embodiment of the present disclosure, the imaging capsule coil is a 3D coil with three orthogonal windings transmitting simultaneously at three different frequencies. Alternatively, the coil of the contrast capsule is a 3D coil having windings in three orthogonal directions that are transmitted in order.

  In an exemplary embodiment of the present disclosure, the recorder comprises at least two 3D coils having windings in three orthogonal directions, and contrast is detected by detecting a direction in which the amplitudes of the at least two 3D coils coincide. The position of the capsule. If necessary, this match takes into account positional differences between at least two 3D coils.

  In an exemplary embodiment of the present disclosure, both the imaging capsule and the recorder include a magnetometer and an accelerometer. If desired, the contrast capsule communicates the display from the magnetometer and / or accelerometer to the recorder using a transceiver. In one exemplary embodiment of the present disclosure, the display is communicated with a time stamp. If necessary, the recorder determines the spatial orientation of the contrast capsule based on magnetometer and accelerometer displays received from the contrast capsule. In an exemplary embodiment of the present disclosure, the recorder determines the position of the imaging capsule based on the determined spatial orientation and transmission of the imaging capsule coil. If necessary, the system further comprises a reference patch having elements similar to the contrast capsule, and the reference patch is attached to the user's body, and the recorder displays the display from the contrast capsule with the reference patch. Compared with, eliminates errors that arise from the movement of the recorder. In an exemplary embodiment of the present disclosure, the recorder uses an adaptive filter to improve the signal-to-noise ratio of the transmission received from the contrast capsule coil. Optionally, the contrast capsule coil includes windings in a single plane. In an exemplary embodiment of the present disclosure, the recorder coil is a 3D coil with windings in three orthogonal directions.

  Thus, in an exemplary embodiment of the present disclosure, a method for estimating the position of a contrast capsule for examining the user's digestive tract is further provided, the method including swallowing the contrast capsule and the user's Inspect the inside, install a recorder that communicates with the contrast capsule outside the user's body, program the contrast capsule controller to control the function of the contrast capsule, and program the recorder controller Controlling the function of the recorder, using the contrast capsule transceiver and the recorder transceiver to communicate information between the contrast capsule controller and the recorder controller, and from the coil of the contrast capsule to the electromagnetic signal Transmitting, receiving an electromagnetic signal by the coil of the recorder, Analyzing the amplitude of the electromagnetic signal transmitted by the coil, and determining a position of the imaging capsule.

  In one exemplary embodiment of the present disclosure, the imaging capsule coil is a 3D coil with three orthogonal windings transmitting simultaneously at three different frequencies. Alternatively, the coil of the contrast capsule is a 3D coil having windings in three orthogonal directions that are transmitted in order. If necessary, the recorder includes at least two 3D coils having windings in three orthogonal directions, and determines the position of the contrast capsule by detecting a direction in which the amplitudes of the at least two 3D coils coincide with each other. To do. In an exemplary embodiment of the present disclosure, both the imaging capsule and the recorder include a magnetometer and an accelerometer. If desired, the contrast capsule communicates the display from the magnetometer and / or accelerometer to the recorder using a transceiver.

  The present disclosure may be understood and better appreciated by reading the following detailed description in conjunction with the drawings. The same structures, elements or parts in more than one figure are typically given the same or similar reference in all the figures in which they exist.

1 is an overview of a system for estimating the position of a contrast capsule in a user's body, according to an exemplary embodiment of the present disclosure. FIG. FIG. 3 is an overview of a contrast capsule, according to an exemplary embodiment of the present disclosure. FIG. 2 is an overview of a recorder, according to an exemplary embodiment of the present disclosure. FIG. 6 is a schematic view of a reference patch for use in a system for estimating the position of a contrast capsule, according to an exemplary embodiment of the present disclosure. FIG. 3 is a schematic diagram of an adaptive filter that improves the accuracy of position estimation of a contrast capsule, according to an exemplary embodiment of the present disclosure. 2 is an overview of a magnetic field transmitted and received by a contrast capsule and recorder, according to an exemplary embodiment of the present disclosure. FIG. FIG. 2 is a vector overview showing magnetic fields transmitted and received by a contrast capsule and recorder, according to an exemplary embodiment of the present disclosure.

  FIG. 1 is an overview of a system 100 for estimating the position of a contrast capsule 110 within a user's body. In an exemplary embodiment of the present disclosure, a user swallows the contrast capsule 110. This capsule enters the digestive tract and is particularly useful for imaging and mapping the small intestine and colon 190. In an exemplary embodiment of the present disclosure, the system 100 includes a recorder 120 that communicates 130 with the contrast capsule 110 and records information provided by the contrast capsule 110. If necessary, the recorder can be coupled to a strap or belt 180 so that when the small intestine and colon 190 are examined with the contrast capsule 110, it is secured to the user's body in close proximity to the small intestine and colon 190. Keep it. The recorder may be placed on the front of the user, on the back of the user, or at any selected location. If necessary, this position is empirically selected to provide an optimal display from the transmission provided by the contrast capsule 110. In an exemplary embodiment of the present disclosure, the recorder 120 analyzes the transmission from the contrast capsule 110 to determine the spatial position of the contrast capsule 110 relative to the recorder 120.

  FIG. 2 is a schematic view of a contrast capsule 110 according to an exemplary embodiment of the present disclosure. If necessary, the capsule 110 includes a coil 240 that transmits a low-frequency electromagnetic wave at 1 to 50 Khz, for example. Alternatively, an electromagnetic signal may be transmitted at approximately 7-14 MHz, and this signal is used for both localization and data transmission using a one-chip communication system such as NxH2180 from NXP Semiconductors, Eindhoven, The Netherlands. Can be used for

  According to this embodiment, communication information is extracted from the coil with a good signal-to-noise ratio (SNR).

  The transmission is received by the recorder 120 and the amplitude thereof is analyzed to determine the position of the contrast capsule 110. In some embodiments of the present disclosure, the windings of coil 240 are in a single plane. Alternatively, the coil 240 may include windings in two or three orthogonal planes (a coil having windings in two orthogonal planes is referred to as a 2D coil, and a coil having windings in three orthogonal planes. Called 3D coil). As needed, 3D coils transmit in three orthogonal directions and use more energy than coils transmitting in a single plane. Thus, in some embodiments of the present disclosure, the imaging capsule 110 is designed to use a single planar coil 240 to save power (eg, supplied by the battery 270) and be power efficient. Allows a relatively large coil to be improved. On the other hand, a 3D coil may be used for the recorder 120 located outside the user's body because the power source can be made larger and can be easily replaced when necessary.

  In an exemplary embodiment of the present disclosure, the imaging capsule 110 includes a magnetometer 230 that functions as a 3D geomagnetic sensor (eg, MAG3110 from Freescale Semiconductors Ltd, Austin, Texas). Alternatively or additionally, the contrast capsule 110 includes an accelerometer 220 that has the function of sensing changes in the position of the contrast capsule 110, for example, in the colon 190. One example of a small accelerometer that can be incorporated into the contrast capsule 110 is MMA7260QT manufactured by Freescale Semiconductors LTD. In some embodiments of the present disclosure, a combined magnetometer and accelerometer device such as, for example, FXOS8700CQ from Freescale Semiconductors LTD may be used.

  In an exemplary embodiment of the present disclosure, the imaging capsule 110 includes a controller 250 and a transceiver 260 to control the functionality of the imaging capsule 110 and to communicate with the recorder 120. The controller 250 may include a processor and / or memory to receive and execute software instructions. If desired, the controller 250 can receive, for example, scan start and scan stop instructions through the transceiver 260. In addition, the controller 250 can transmit images recorded by the contrast capsule 110 and information regarding the spatial position of the contrast capsule 110, such as a display of the magnetometer 230 and / or the accelerometer 220. If desired, this information can inform the recorder 120 about the orientation of the contrast capsule 110 and coil 240 relative to the earth's magnetic and gravitational fields.

  FIG. 3 is an overview of the recorder 120 according to an exemplary embodiment of the present disclosure. The recorder 120 may include a controller 350, a transceiver 360, a magnetometer 330, an accelerometer 320, a power source 370, and one or more receive coils 340, if desired. If desired, the one or more receive coils 340 may be single plane coils or may have windings in two or three orthogonal planes (2D coils or 3D coils). In an exemplary embodiment of the present disclosure, one or more receive coils 340 of recorder 120 interact with coil 240 of contrast capsule 110 by receiving a low frequency transmission transmitted from contrast capsule 110. . If necessary, the amplitude of the transmission from the contrast capsule 110 by the combination of the receive coils 340 can be calculated so that the spatial position of the contrast capsule 110 can be calculated and the distance between the recorder 120 and the contrast capsule 110 can be determined. Analysis can be used to determine the direction and distance from the recorder 120.

  In an exemplary embodiment of the present disclosure, an indication from magnetometer 230 and / or accelerometer 220 is transmitted from contrast capsule 110 to recorder 120. Optionally, the recorder 120 compares the display to the display of the magnetometer 330 and / or the accelerometer 320, and the angular orientation of the contrast capsule 110 and coil 240 relative to the direction of the recorder 120 and one or more receive coils 340. To decide. In an exemplary embodiment of the present disclosure, the display of the magnetometer 230 and / or accelerometer 220 is time stamped from the contrast capsule 110 to display the display of the magnetometer 230 and / or accelerometer 220 and the magnetometer. The comparison with the display of 330 and / or accelerometer 320 is synchronized. The space of the contrast capsule 110 relative to the recorder 120 using the amplitude measured by the one or more receiving coils 340 from the transmission of the coil 240 with the angular orientation determined from the display of the magnetometer 230 and / or the accelerometer 220, if desired. Determine the target position.

  In an exemplary embodiment of the present disclosure, the spatial angle of the imaging capsule 110 is obtained by the magnetometer 330 and / or the accelerometer 320, so that, for example, by the controller 350 of the recorder 120, electromagnetic interference to the transmission of the coil 240. Can be specified. Optionally, during magnetic or metallic disturbances, the electromagnetic field is disturbed differently from the earth's constant magnetic field and / or gravity field. Thus, an abrupt change in the amplitude of the transmission from the coil 240 provides an indication of negligible electromagnetic interference without a corresponding change in the spatial orientation of the imaging capsule recorded by the magnetometer 330 and / or accelerometer 320. Can be provided. In some embodiments of the present disclosure, the coil amplitude is processed only when movement of the contrast capsule 110 is detected.

  In one exemplary embodiment of the present disclosure, the distance to the contrast capsule 110 is calculated using two or more receive coils 340 of the recorder 120 without information from the accelerometer 220 and / or the magnetometer 230. In one exemplary embodiment of the present disclosure, the two or more receive coils may have windings in a single plane, or have windings in two or three orthogonal planes. Also good. In some embodiments of the present disclosure, at least one of the receive coils 340 is a 3D coil. If necessary, test all possible directions of the contrast capsule 110 and determine the position by two or more receive coils 340 by selecting a direction that matches the calculated position of the contrast capsule 110. . If necessary, this match takes into account the difference in position between two or more receive coils 340 of the recorder 120. In an exemplary embodiment of the present disclosure, one of the receive coils 340 may be configured so that the transmitter can measure the relative distance and angle between the receive coils 340 of the recorder 120 before calculating the distance to the coil 240. And may serve as a receiver and provide transmission to other receive coils 340. Alternatively, a separate transmit reference coil is used and the distance is calculated against this reference.

  In some embodiments of the present disclosure, the coil 240 of the imaging capsule 110 transmits at three different frequencies simultaneously or at a single frequency so that the receiver can distinguish between the three transmissions. A winding of each plane orthogonal to each other is a 3D coil that transmits in order. If desired, a single plane receive coil 340 may be used to receive transmissions and calculate the current distance from the recorder 120 and contrast capsule 110.

  In one exemplary embodiment of the present disclosure, the recorder 120 includes a container 380 (FIG. 3). Optionally, the container 380 is coated with a high permeability material that protects the elements of the recorder 120 from the effects of extracorporeal magnetic fields, such as MuMetal from The MuShield Company of Londonderry, New Hampshire. In one exemplary embodiment of the present disclosure, the side facing the user's body is not coated to receive transmissions from the contrast capsule 110 from within the user's body. If necessary, if there is a shielding effect, the recorder 120 calibrates it so that it is protected from external electromagnetic interference.

  FIG. 4 is an overview of the reference patch 410 used in the system 100 for estimating the position of the contrast capsule 110. In one exemplary embodiment of the present disclosure, the reference patch 410 is as small as the imaging capsule 110 and includes similar elements, such as an accelerometer 420, a magnetometer 430, a coil 440, a controller 450, and a transceiver 460. If necessary, the reference patch 410 is attached to the user by, for example, being adhesively disposed on the user's back. The reference patch 410 functions as a fixed reference for the contrast capsule 110 that moves dynamically through the user's digestive tract. The recorder 120 communicates with the reference patch 410 and the contrast capsule 110 as needed.

  In an exemplary embodiment of the present disclosure, the recorder 120 calculates the position of the contrast capsule 110 relative to the reference patch 410 and is bulkier than the reference patch 410 if necessary and attached to the belt 180 to attach to the user's body. Since it does not have to be glued to the head, it reduces the recording of false movements resulting from movement of the recorder 120 that is more sensitive to movement. In some embodiments of the present disclosure, the recorder 120 may be replaced with the form of the recorder 120 shown in FIG. 1 so that the recorder 120 only needs to communicate with the contrast capsule 110 and does not need to communicate with an additional reference patch. , In the form of a reference patch 410 (eg, in the form of a small patch attached to the user shown in FIG. 4). In some embodiments of the present disclosure, the reference patch 410 may also send a signal from the coil 440 to the contrast capsule 110 to test, for example, communication range.

  FIG. 5 is an overview of an adaptive filter 500 that improves the accuracy of position estimation of the contrast capsule 110. In an exemplary embodiment of the present disclosure, recorder 120 uses an adaptive filter (eg, in controller 350) to transmit received from contrast capsule 110 (eg, from a signal received by receive coil 340). And improve the signal-to-noise ratio (SNR). If necessary, it is possible to reduce noise in the adaptive filter 500 by estimating the noise in the environment while the contrast capsule 110 is not transmitting (noise while the contrast capsule 110 is transmitting). Is similar to noise when not transmitting). In an exemplary embodiment of the present disclosure, a signal (including noise) received by the recorder 120 from the contrast capsule 110 is input to the input 540 of the adaptive filter 500. If necessary, the estimated noise measured while the contrast capsule 110 is not transmitting is recorded and input to the noise input 550. Filter 510 accepts the signal from noise input 550 and is prepared to combine with the input signal to cancel the noise from this input signal. An adder 520 combines the input signal with the processed noise and supplies this combined signal as an output signal to the output 560. In addition, this output signal is provided as feedback from the signal to noise ratio controller 530 to the filter 510 to improve the processing of the input signal and maximize the signal to noise ratio.

  An exemplary closed form analytical solution for calculating the distance from the recorder 120 to the contrast capsule 110 according to an exemplary embodiment of the present disclosure will now be described. Optionally, in this calculation, the spatial orientation of the contrast capsule 110 relative to the recorder 120 is wound on orthogonal planes of the accelerometer 220, accelerometer 320, magnetometer 230, magnetometers 330, 1-3. And a single receiving coil 340 having windings in three orthogonal planes.

によって表されるベクトル振幅Ｂ＝（Ｂ_ｘ，Ｂ_ｙ，Ｂ_ｚ）を有する低周波磁場を生じる。
ここで、ｎは、カプセルコイル法線ベクトル（コイル２４０からの送信を表す）であり、ｒは、コイル中心の動径である。
受信機のｉ番目のコイルに誘起される振幅は：
式（２）

である。
ここで、ｎ_ｉは、ｉ番目のコイル法線ベクトルである。

ここで、μ_０＝４π １０^−７Ｖｓ／（Ａｍ）は真空の透磁率、Ｉ_ｃはカプセルコイルの電流、Ｎ_ｃはカプセルコイルの巻き数、ａ_ｃはカプセルコイルの有効半径、ｎ＝（ｎ_ｘ，ｎ_ｙ，ｎ_ｚ）はカプセルコイル法線ベクトル、およびｒ＝（ｘ−ｘ_０，ｙ−ｙ_０，ｚ−ｚ_０）は観測点（ｘ_０，ｙ_０，ｚ_０）およびカプセルコイルの中心（ｘ，ｙ，ｚ）間のデカルト距離ベクトルである。

ここで、ｆはフィールド周波数、Ｎ_ｉはｉ番目のコイル巻き数、ａ_ｉはｉ番目のコイルの有効半径、ｎ_ｉ＝（ｎ_ｘｉ，ｎ_ｙｉ，ｎ_ｚｉ）はｉ番目のコイル法線ベクトル、およびＢ_ｉはｉ番目のコイル中心の磁場である。 The induction coil 240 is a magnetic dipole:
Formula (1)

Produces a low-frequency magnetic field having the vector amplitude B = (B _x , B _y , B _z ) represented by
Here, n is a capsule coil normal vector (representing transmission from the coil 240), and r is a moving radius of the coil center.
The amplitude induced in the i th coil of the receiver is:
Formula (2)

It is.
Here, _ni is the i-th coil normal vector.

Here, μ ₀ = 4π 10 ⁻⁷ Vs / (Am) is the magnetic permeability of vacuum, I _c is the current of the capsule coil, N _c is the number of turns of the capsule coil, a _c is the effective radius of the capsule coil, and n = ( n _x , n _y , n _z ) is the capsule coil normal vector, and r = (x−x ₀ , y−y ₀ , z−z ₀ ) is the observation point (x ₀ , y ₀ , z ₀ ) and capsule. It is a Cartesian distance vector between coil centers (x, y, z).

Where f is the field frequency, N _i is the number of turns of the i th coil, a _i is the effective radius of the i th coil, and n _i = (n _xi , n _yi , n _zi ) is the i th coil normal vector. , And B _i are the magnetic fields at the center of the i th coil.

ここで、ρは、正規化ベクトルｒである。
よって：

とする。
そこで、以下が得られる：

次に、（ｍ）を定義し、代入によって式（３）が得られる：

Next, the vector r is calculated from the known amplitude value and the coil normal vector. First, when r is a solution, it can be seen that -r is also a solution. From the physical problem and / or tracking history, an appropriate solution can usually be selected.
Substituting equation (1) into equation (2) yields:

Here, ρ is a normalized vector r.
Hence:

And
So you get:

Next, define (m) and substitute to obtain equation (3):

と表す。
そして、これより以下を得る。

したがって、ケース（Ｓ）を２つのサブケースに分けてもよい：

Ｓ１について、式は次のようになる：

そして、Ｓ２について、次を得る：

図６に示すように、ｒ_０は、原点に中心を有し、かつｎに対して直交するよう配向された円（Ｏ）の半径である。そして、Ｏのすべての点が（１）の解である。したがって、受信した振幅を追跡することによって、この解を見つけることができる。 As shown in FIG. 6, the normal vector of transmission by the coil 240 (n) and the normal vector of reception by the coil 340 (m) are parallel (ie, m // n) and two sub cases (S1) and (S2). Consider the special case set as (S) with (parallel and antiparallel).
This means that the magnetic field B is parallel to the capsule direction n and B = kn.
From (1) above, we can see:

It expresses.
And the following is obtained from this.

Therefore, case (S) may be divided into two subcases:

For S1, the formula is:

And for S2, we get:

As shown in FIG. 6, r ₀ is the radius of a circle (O) centered at the origin and oriented perpendicular to n. And all the points of O are solutions of (1). Therefore, this solution can be found by tracking the received amplitude.

FIG. 7 shows the normal vector for transmission by coil 240 (n) and the normal vector for reception by coil 340 (m) in the general case when not parallel. Therefore, in non-special time (not S), both sides are multiplied from the left by the following.

式（４）を得る：

（５）の両辺を２乗し、複二次方程式を解く。

It can be seen that the vector ρ is in the same plane with respect to the vectors n and m.
Let μ be the normalization vector of the m and n planes orthogonal to n.
Multiply equation (3) by n and μ in view of the following:

Obtain equation (4):

Square both sides of (5) to solve the double quadratic equation.

よって、γ^２：ｇ_１およびｇ_２に２つの実数解がある。ビエタの公式（Ｖｉｅｔａ ｆｏｒｍｕｌａｓ）から以下が分かる。

（５）より、また、0≦γ²≦あることが分かる。最後に、

式

の解ｇ_１，２を選択することができる。
η=0の場合が特に重要である。この場合

であることが分かる。
最後に、（４）から以下を得る：

For γ, the discriminant is

Thus, there are two real solutions for γ ² : g ₁ and g ₂ . The following can be seen from the Vita formula.

From (5), it can also be seen that 0 ≦ γ ² ≦. Finally,

formula

The solutions g ₁ and ₂ can be selected.
The case of η = 0 is particularly important. in this case

It turns out that it is.
Finally, from (4) we get:

よって、ρの値によって距離が分かる。
必要に応じて、前回の位置データ、たとえば特異点に近い履歴位置を使用して、特別なケースに関する不明確さを解決する。 The last step is

Therefore, the distance can be determined by the value of ρ.
If necessary, use previous location data, eg, historical locations close to singularities, to resolve ambiguities for special cases.

  It should be appreciated that the methods and apparatus described above may be varied in many ways, including omission or addition of steps, order of steps and changes in the type of equipment used. It should be appreciated that different features may be combined in various ways. In particular, not all features described above in one particular embodiment are essential to all embodiments of the disclosure. Further combinations of the above features are also considered within the scope of some embodiments of the present disclosure. It will also be appreciated by persons skilled in the art that the present disclosure is not limited to what has been particularly shown and described hereinabove.

Claims (20)

A system for estimating the position of a contrast capsule for examining a user's digestive tract,
A contrast capsule for examining the inside of the user;
A recorder that communicates with the contrast capsule from outside the user,
The contrast capsule is
A controller for controlling the function of the contrast capsule;
A transceiver in communication with the recorder;
A coil for transmitting electromagnetic signals,
The recorder is
A controller for controlling the function of the recorder;
A transceiver in communication with the contrast capsule;
A coil for receiving an electromagnetic signal from the coil of the contrast capsule;
The recorder determines a position of the contrast capsule based on a measured value of the amplitude of the electromagnetic signal transmitted by the coil of the contrast capsule.   The system of claim 1, wherein the contrast capsule coil is a 3D coil having three orthogonal windings transmitting simultaneously at three different frequencies.   The system according to claim 1, wherein the coil of the contrast capsule is a 3D coil having windings in three orthogonal directions that transmit in order.   The recorder comprises at least two 3D coils having windings in three orthogonal directions, and determines a position of the contrast capsule by detecting a direction in which the amplitudes of the at least two 3D coils coincide with each other. Item 4. The system according to Item 1.   The system of claim 4, wherein the match takes into account a positional difference between the at least two 3D coils.   The system of claim 1, wherein both the imaging capsule and the recorder include a magnetometer and an accelerometer.   The system of claim 6, wherein the contrast capsule communicates a display from the magnetometer and / or the accelerometer to the recorder using the transceiver.   The system of claim 7, wherein the indication is communicated with a time stamp.   8. The system of claim 7, wherein the recorder determines a spatial orientation of the contrast capsule based on a display of the magnetometer and accelerometer received from the contrast capsule.   10. The system of claim 9, wherein the recorder determines the position of the contrast capsule based on the determined spatial orientation and transmission of the contrast capsule coil.   The system further comprises a reference patch having elements similar to the contrast capsule, the reference patch is attached to a user's body, and the recorder displays the display from the contrast capsule with the display from the reference patch. The system of claim 1, wherein, in comparison, errors resulting from movement of the recorder are eliminated.   The system of claim 1, wherein the recorder uses an adaptive filter to improve the signal-to-noise ratio of transmissions received from the coils of the contrast capsule.   The system of claim 1, wherein the imaging capsule coil comprises a winding in a single plane.   The system according to claim 1, wherein the coil of the recorder is a 3D coil having windings in three orthogonal directions. A method for estimating the position of a contrast capsule for examining a user's digestive tract,
Swallowing the contrast capsule and examining the inside of the user;
Attaching a recorder communicating with the contrast capsule outside the user's body;
Programming the contrast capsule controller to control the function of the contrast capsule, and programming the recorder controller to control the function of the recorder;
Communicating information between the contrast capsule controller and the recorder controller using the contrast capsule transceiver and the recorder transceiver;
Transmitting an electromagnetic signal from a coil of the contrast capsule;
Receiving the electromagnetic signal by a coil of the recorder;
Analyzing the amplitude of the electromagnetic signal transmitted by the coil to determine the position of the contrast capsule.   16. The method of claim 15, wherein the imaging capsule coil is a 3D coil having three orthogonal windings transmitting simultaneously at three different frequencies.   The method according to claim 15, wherein the coil of the contrast capsule is a 3D coil having windings in three orthogonal directions that transmit in sequence.   The recorder comprises at least two 3D coils having windings in three orthogonal directions, and determines a position of the contrast capsule by detecting a direction in which the amplitudes of the at least two 3D coils coincide with each other. Item 16. The method according to Item 15.   The method of claim 15, wherein both the imaging capsule and the recorder comprise a magnetometer and an accelerometer.   20. The method of claim 19, wherein the contrast capsule communicates a display from the magnetometer and / or the accelerometer to the recorder using the transceiver.

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